private void CreateErrorReply(ref RequestContext requestContext)
        {
            using (var sr = new StringReader("<?xml version=\"1.0\" encoding=\"utf-8\"?>" + ErrorHtml))
            {
                XElement response = XElement.Load(sr);
                using (Message reply = Message.CreateMessage(MessageVersion.None, null, response))
                {
                    var responseProp = new HttpResponseMessageProperty
                    {
                        StatusCode = HttpStatusCode.Forbidden,
                        StatusDescription = String.Format("Forbidden")
                    };
                    responseProp.Headers.Add("WWW-Authenticate", String.Format("Basic realm=\"{0}\"", Realm));
                    responseProp.Headers[HttpResponseHeader.ContentType] = "text/html";
                    reply.Properties[HttpResponseMessageProperty.Name] = responseProp;
                    requestContext.Reply(reply);

                    requestContext = null;
                }
            }
        }